Answer:the number of cars that were washed is 50
Step-by-step explanation:
Let x represent the number of cars that members of a senior class.
Let y represent the number of pick-up truck or a sport utility vehicle that members of a senior class.
They charged $3 to wash a car and $5 to wash a pick-up truck or a sport utility vehicle and they earned a total of $275. This means that
3x + 5y = 275 - - - - - - - - -- - -1
They washed a total of 75 vehicles. This means that
x + y = 75
Substituting x = 75 - y into equation 1, it becomes
3(75 - y) + 5y = 275
225 - 3y + 5y = 275
- 3y + 5y = 275 - 225
2y = 50
y = 50/2 = 25
Substituting y = 25 into x = 75 - y, it becomes
x = 75 - 25 = 50
